Continuous renal replacement therapy: are we getting the dose right?

Introduction

The Intensive Care Society recommends achieving a dose of 35 ml/kg/hour in 85% of patients receiving continuous renal replacement therapy (CRRT). However, a recent multicentre trial concluded there was no benefit of using 40 ml/kg/hour versus 25 ml/kg/hour. The extra cost of high-dose RRT has not been quantified. At our institution the target dose is 35 ml/kg/hour.

Methods

Patients receiving renal replacement therapy from April to September 2009 were identified using Careview, an electronic patient-care record system. The effluent rate (ml/hour) was used to calculate the dose and adjusted for weight. A telephone survey of ICUs examined the dose and mode of CRRT used in Scotland.

Results

Thirty-five patients, mean age 62, received CRRT with a mean duration of RRT of 78 hours. Twenty-three patients (66%) were admitted with sepsis. Continuous venovenous haemodiafiltration was the initial mode in 31 patients (89%). Ten patients were excluded from the dose analysis because no weight was documented. The mean dose actually delivered per patient was 50 ml/kg/hour. If 25 ml/kg/hour had been given then 40% less RRT fluid could have been used. The Scottish telephone survey revealed that one-third of Scottish ICUs routinely use 35 ml/kg/hour or more. If 25 ml/kg/hour was used routinely in these units alone, then over €24,000 could be saved per annum.

Conclusions

The dose of CRRT given for each patient at our institution currently exceeds the target dose by 43%. Using 25 ml/kg/hour as the standard dose would provide a significant cost saving to the NHS in Scotland and to ICUs throughout Europe.

Figure 1

Mean does of RRT for each patient at Western infirmary.